Aluminum alloy plate for lithographic printing form and method for production thereof and lithographic printing form

ABSTRACT

The present invention provides an aluminum alloy plate for use as a lithographic printing plate having an improved uniformity of a surface roughened by electrolytic etching and wherein streaking does not occur, and a method for producing the same. The present invention is characterized in comprising, in wt %, Fe: 0.1 to 0.6%; Si: 0.02 to 0.2%; Cu: 0.001 to 0.02%; Zn: 0.01 to 0.1%; Mg: 0.005 to 0.1%; Ti: 0.001 to 0.05%, and the remainder Al and inevitable impurities, and an average value of the crystal particle size is 60 μm or less in a direction perpendicular to the rolling direction.

This application is a U.S. national phase application of PCTInternational phase application number PCT/JP02/13839 filed Dec. 27,2002.

TECHNICAL FIELD

The present invention relates to an aluminum alloy plate for use as alithographic printing plate on which a photosensitive layer is formed inadvance and which is used as is or after a developing process or afterthe photosensitive layer is subjected to a printing process, and amethod for manufacturing the same, and in particular relates to atechnique for providing an aluminum alloy plate and a lithographicprinting plate having excellent uniformity of a surface roughened byelectrolytic etching.

BACKGROUND ART

In lithographic printing, a presensitized plate comprising aphotosensitive body of a diazo compound or the like and an aluminumalloy plate is subjected to processing such as image exposure,developing and the like to obtain a plate on which an image portion hasbeen formed, and is wrapped around the cylindrical plate drum of apress, and under the presence of moisturizing water adhered to thenon-image portions, ink is adhered to the image portions, and thisadhered ink is transferred to a rubber blanket, and printed on thesurface of a paper.

As the support body of the above presensitized plate, it is usual to usean aluminum alloy plate which has been subjected to a surface treatmentsuch as a roughening process by electrolytic etching (graining), ananodic oxidation treatment or the like. As an aluminum alloy used forthis type of application, JIS 1050 (pure Al, having a purity 99.5% andabove), JIS 1100 (an alloy of Al and 0.05 to 0.20% Cu) and JIS 3003 (analloy of Al, 0.05 to 0.20% Cu, and 1.5% Mn) were mainly used at first.

Various characteristics are required for this type of aluminum alloyplate for use as a lithographic printing plate, such as:

(1) A surface uniformly roughened by electrolytic etching.

(2) Good adhesiveness for a photosensitizer.

(3) Contamination does not arise at the image portion during printing.

However, because the products specified by JIS 1050, JIS 1100, and JIS3003 cannot sufficiently satisfy all of the above requirements, manyimprovements have been made to the alloy compositions and the state ofthe surface that can be obtained.

For example, the surface roughening process is carried out to fix andadhere the photosensitive layer, in addition to providing waterretentivity to the surface of the aluminum alloy plate. However, withprior surface roughening treatments, unetched portions would arise onthe roughened surface, and the distribution of the pits formed by thesurface roughening was uneven, which had considerably adverse effect onthe performance of the printing plate, and there has been demand toimprove the surface state.

In the past, from the above viewpoint, improvements in materials havebeen tested, and as one method, it has been proposed to add specialelements to the material. For example, Japanese Unexamined PatentApplication, First Publication No. Hei 11-115333 discloses a methodwherein by the addition of a predetermined amount of Ni, the formationof pits is promoted, and the etchability is increased; JapaneseUnexamined Patent Application, First Publication No. Sho 58-210144discloses a method wherein by the addition of Sn, In and Ga, micropitsare formed and the etchability is increased.

However, even if the above special elements are added, the abovementioned requirements cannot be met, and further, by adding theseparticular elements, there are the problems that increases in materialcosts are incurred, and the recyclability is impaired.

Further, a method has been proposed for improving the etchabilitywithout adding special elements, by focusing on and controlling the sizeand density of the intermetallic compound (Japanese Unexamined PatentApplication, First Publication No. Hei 11-151870). In this method, theintermetallic compound becomes the starting point of the etching, andmicropits are uniformly formed. However, the etchability according tothis method cannot be sufficiently improved, and the above requirementscannot be satisfied.

Based on the research of the present inventors, it was learned that itis not possible to obtain sufficient etchability by controlling the sizeand density of the above intermetallic compounds, because the chemicalsolubility of these intermetallic compounds is unexpectedly large, andthey dissolve in the electrolytic solution, and are eliminated, and as aresult, they do not sufficiently function as the starting points ofetching pits. As a result of further progress in their research, it wasfound that by moderately dispersing particles of a metastable AlFe typeintermetallic compound, the etchability is greatly improved, and theabove requirements can be sufficiently met.

Further, the present inventors learned as a result of further progressin research on this type of presensitized plate, that in the case ofsubjecting an aluminum alloy plate to an electrolytic etching process byimmersion in an electrolytic treatment solution, as the aluminum plateis moved from the roll, at right angles to the direction of the aluminumplate (the direction of moving the aluminum plate), streaking, theprimary cause of uneven etching, readily occurs on the aluminum plate.This streaking occurs especially readily when the line speed isincreased and the electrolytic etching treatment time is short, and atthe portions where unevenness arises, i. e., at the portions where thesurface roughening is shallow, the streaking remains even in the finalstate of the product of a presensitized plate provided with aphotosensitive layer, and this is connected with an unfavorable externalappearance, and there is great concern that the adhesion of thephotosensitive film will be low and the durability will be reduced.

Further, for this type of presensitized plate, in some types ofproducts, an even higher degree of strength is demanded. For example, inthe case that the presensitized plate is chucked on a roll, a bend ismade at the end portion to fix and wrap it around the print cylinder,but this bend is in a direction perpendicular to the direction ofrolling, namely it occurs in a direction parallel to the abovestreaking, and therefore there is the problem that there is concern ofcracks arising in the presensitized plate when it is bent.

For example, in order to prevent the occurrence of the above streaking,it can be considered to subject it to a strong electrolytic etchingtreatment, but the present inventors discovered that as a result ofthis, the anode site undergoes stronger etching than the cathode site,and therefore, pits which are initially moderately formed have atendency to become overetched, and these overetched portions can easilyoverlap the above mentioned bent portions. If the above cracks developin a presensitized plate, ruptures are likely to form with these cracksas their origin.

DISCLOSURE OF THE INVENTION

The present invention has the objective of providing an aluminum alloyplate for use as a lithographic printing plate which is not subject tothe occurrence of streaking, which has few unetched portions, and whichby electrolytic etching so as to make the pits uniform, has improveduniformity of the surface roughening, without requiring the addition ofspecial chemical elements, and a method for producing the same.

Further, the present invention has the objective of providing analuminum alloy plate for use as a lithographic printing plate where theuniformity of the surface roughening is improved, and streaking does notoccur, and at the same time, which has improved strength, and does notreadily crack at the time of mounting onto a print cylinder, and whererupturing does not occur, and a method for producing the same.

By their research, as a result of their consideration of the mechanismwhich originates the above streaking, the present inventors found thatthe occurrence of streaking relates to the frequency of the AC currentused for the electrolytic etching.

That is, the reason for the streaking of the surface of the aluminumalloy plate is believed to be as follows. In the aluminum alloy plateimmersed in the electrolytic solution, at the portion to which theanodic current is applied (the anode portion), the aluminum is dissolvedby the reaction Al→Al³⁺+3e⁻, and pits are formed and the color becomeswhite. On the other hand, at the portion to which the cathodic electriccurrent is applied (the cathode portion), there is only production ofgas by the reaction 2H⁺+2e⁻→H₂, and there is almost no solvation of thealuminum. As a result, it was found that streaking is formed dependingon the frequency of the AC current.

The present invention was made by advancing the study of thecharacteristics of aluminum alloy materials in order to control thegeneration of streaking based on such a generation mechanism.

The aluminum alloy plate for use as a lithographic printing plate of thepresent invention comprises, in wt %, Fe: 0.1 to 0.6%; Si: 0.02 to 0.2%;Cu: 0.001 to 0.02%; Zn: 0.01 to 0.1%; Mg: 0.005 to 0.1%; Ti: 0.001 to0.05%, and the remainder Al and inevitable impurities, and the averagevalue of the crystal particle size in the direction perpendicular to thedirection of rolling is 60 μm or less.

The aluminum alloy plate for use as a lithographic printing plate of thepresent invention includes a plurality of intermetallic compoundparticles within the metallic structure of the above disclosedinvention, and is characterized in that in said intermetallic compoundparticles, the value of the ratio A/B is 0.2 or more, where A is thenumber of said intermetallic compound particles having anequivalent-circle diameter of 0.1 to 1.0 μm, and B is the total numberof particles of 0.1 μm or above.

The aluminum alloy plate for use as a lithographic printing plate of thepresent invention includes a plurality of intermetallic compoundparticles in the metallic structure of the above mentioned invention,and is characterized in that in said intermetallic compound particles,the value of (D/E)×100 is 0.2 or more, where D is the included amount ofintermetallic compound particles having an equivalent-circle diameter of0.1 μm or more and less than 1.0 μm, and E is the included amount ofparticles having an equivalent-circle diameter of 1.0 μm or more.

The aluminum alloy plate for use as a lithographic printing plate of thepresent invention is characterized in that the above amounts of Cu, Fe,Zn and Mg satisfy the relationship equation: 0.15≧Zn+Mg−(Fe/10)−Cu.

The aluminum alloy plate for use as a lithographic printing plate of thepresent invention is characterized in that in the composition of saidintermetallic compound particles, the value of C/B is 0.35 or above,where C is the number of metastable phase particles with a Fe/Al ratioof 0.6 or less, and B is the total number of intermetallic compoundparticles.

The aluminum alloy plate for use as a lithographic printing plate of thepresent invention is characterized in that it comprises a metastabledispersion layer comprising a metastable phase of AlFe typeintermetallic compound particles dispersed in at least its surface layerportion.

The production method of the present invention is a method for producingan aluminum plate for use as a lithographic printing plate characterizedin comprising, in wt %, Fe: 0.1 to 0.6%; Si: 0.02 to 0.2%; Cu: 0.001 to0.02%; Zn: 0.01 to 0.1%; Mg: 0.005 to 0.1%; Ti: 0.001 to 0.05%, and theremainder Al and inevitable impurities, and having an average value ofthe crystal particle size in the direction perpendicular to the rollingdirection of 60 μm or less, the method being characterized in thatingots of the alloy of said composition are subjected to a homogenizingtreatment at 550° C. or less, or subjected to soaking without beingsubjected to a homogenization treatment, and hot rolled.

The production method of the present invention is characterized in beinga method for producing an aluminum alloy plate for use as a lithographicprinting plate comprising a plurality of intermetallic compoundparticles in its metallic structure, and in said intermetallic compoundparticles, the value of A/B is 0.2 or above, where A is the number ofsaid intermetallic compound particles having an equivalent-circlediameter of 0.1 to 1.0 μm, and B is the total number of particles havingan equivalent-circle diameter of 0.1 μm and above.

The production method of the present invention is characterized in beinga method for producing an aluminum alloy plate for use as a lithographicprinting plate comprising a plurality of intermetallic compoundparticles in its metallic structure, and in terms of theequivalent-circle diameter, in said intermetallic compound particles,the value of (D/E)×100 is 0.2 or more in terms of equivalent-circlediameter of 0.1 μm or above, where D is the amount of intermetalliccompound particles less than 1.0 μm, and E is the amount of particles1.0 μm or more.

The production method of the present invention is characterized in beinga method for producing an aluminum alloy plate for use as a lithographicprinting plate wherein, in the composition of said intermetalliccompound particles having a particle diameter of 0.1 μm or more, thevalue of C/B is 0.35 or less, where C is the number of metastableparticles having a Fe/Al ratio of 0.6 or less, and B is the total numberof intermetallic compound particles.

The production method of the present invention is characterized in beinga method for producing an aluminum alloy plate for use as a lithographicprinting plate comprising a metastable dispersion layer with metastablephase AlFe type intermetallic compound particles dispersed in at leastits surface layer portion.

The lithographic printing plate of the present invention ischaracterized in that a photosensitive layer is provided on the aluminumalloy plate for use as a lithographic printing plate, wherein any of thepreceding aluminum plates is subjected to at least a surface rougheningor an anodic oxidation treatment.

The invention explained above has a composition comprising in wt %, Fe:0.1 to 0.6%; Si: 0.02 to 0.2%; Cu: 0.001 to 0.02%; Zn: 0.01 to 0.1%; Mg:0.005 to 0.1%; Ti: 0.001 to 0.05%, and the remainder Al and inevitableimpurities, and the average crystal particle size in the directionperpendicular to the direction of rolling is 60 μm or less, andtherefore,

the intermetallic compound particles of all sizes which can be thestarting points for reactions can be uniformly distributed, and byproviding a metastable phase of an intermetallic compound, in the caseof electrolytic etching, as a result of being able to obtain a goodbalance of both the reactions at the anode portion and the cathodeportion, it is possible to obtain an aluminum plate for use as alithographic printing plate where streaking does not occur.

Further, in the present invention, an appropriate amount of Mn is addedto improve the strength, and therefore, the rupture resistance and thedurability are excellent, and at the same time, along with the additionof Mg, the alloy elements of Fe, Si, Cu, Zn and Ti are included within arange of amounts, and therefore, in addition to providing ruptureresistance and durability, it is possible to provide an aluminum alloyplate where streaking does not occur.

Further, by setting the value of A/B to 0.2 or more, as a result ofbeing able to further improve the balance of the reactions at the anodeportion and the cathode portion, it is possible to obtain an aluminumalloy plate for use as a lithographic printing plate where streakingdoes not occur, and having an even more excellent performance withrespect to rupture resistance and durability. Further, an aluminum alloyplate comprising a metastable dispersion layer where a metastable phaseof AlFe intermetallic compound particles are dispersed in at least asurface portion of the plate can be preferably applied to the presentinvention.

Further, according to the production method of the present invention, inthe production of an aluminum alloy plate for use as a lithographicprinting plate having the above composition and provided with the abovecharacterized intermetallic composition particles, alloy ingots of theabove composition are subjected to a homogenization treatment at atemperature of 550° C. or below, or are subjected to a soaking treatmentwithout being subjected to a homogenization treatment and hot rolled,and therefore, it is possible to obtain an aluminum alloy phase whereinan intermetallic compound which is a metastable phase which is noteliminated can be reliably deposited, and therefore, an aluminum alloyplate for use as a lithographic printing plate wherein streaking doesnot occur and with even more excellent performance concerning ruptureresistance and printing durability can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of the lithographic printing plate of thepresent invention.

BEST MODE FOR CARRYING OUT THE INVENTION

The embodiments of the inventions are explained below, but needless tosay, the present invention is not limited to these embodiments.

The present inventors considered the uniformity of electrolytic etchingof the aluminum alloy support body for use as a presensitized plate inorder to solve the above problems, and discovered the following.

(1) An Al—Fe type intermetallic compound crystallizes or precipitates inthe aluminum matrix, acts as the cathode point during electrolyticetching, and controls the solubility of the aluminum alloy support bodyfor use as a presensitized plate.

(2) The present inventors believed that to control the occurrence of theabove mentioned streaking, it would be effective to increase thesolubility of the material of the cathode portion (the cathodesolubility). Namely, by making the portion receiving the cathodereaction whiten, the difference in appearance between the anode and thecathode is reduced, and the streaking is controlled.

From this point of view, the elements to be added to the aluminum wereconsidered, and the effects of the added elements were studied, and itwas found that for the added components Si, Cu, and Ti, and the like, byincreasing the amount added, the solubility is decreased. However, ifthe added amount of Cu is too low, the solubility of the cathodedecreases, and it became clear that an added amount within the range of0.001 to 0.02% is appropriate. On the other hand, Fe, Zn and Mg increasethe solubility of the cathode, and the best results could be obtained bysetting a relational formula specifying the added amount of Zn and Me,with respect to the added amount of Fe and Cu.

With the above background, in the present embodiments, in order toachieve these types of objectives, it is preferable for an aluminumalloy plate for use as a lithographic printing plate to comprise, in wt%, Fe: 0.1 to 0.6%; Si: 0.02 to 0.2%; Cu: 0.001 to 0.02%; Zn: 0.01 to0.1%; Mg: 0.005 to 0.1%; Ti: 0.001 to 0.05%, and the remainder Al andinevitable impurities, with an average value of the crystal particlesize in the direction perpendicular to the rolling direction of 60 μm orless.

Further, this type of aluminum alloy plate includes intermetalliccompositions (AlFe type, AlFeSi type, Si type, Ti type), and it wasfound that to the extent that these intermetallic compositions arefinely dispersed, the cathode reaction increases, and the streaking canbe reduced.

The conditions for this are, in the previously disclosed intermetalliccomposition particles, in terms of the equivalent-circle diameter, avalue of A/B of 0.2 or above for the case that A is the number ofparticles with an equivalent-circle diameter of 0.1 to 1.0 μm, and B isthe total number of particles. Further, the upper limit for the value ofA/B is on the order of 50, and if the value is higher than this, theeffect of improving the streaking is very small.

Alternatively, as the conditions, in said intermetallic compoundparticles, the value of (D/E)×100 is 0.20 or above in the case that D isthe amount of intermetallic compound particles having anequivalent-circle diameter of 0.1 μm or more and less than 1.0 μm, and Eis the amount of particles of 1.0 or more.

The intermetallic compound particles which effectively control the shapeof the pits have a size of 0.1 μm to 1.0 μm. Intermetallic compoundparticles having a size exceeding 1.0 μm coarsen the pits. Accordingly,it is preferable to have a large amount of particles of 0.1 to 1.0 μm. Avalue of (D/E)×100 of 0.20 or above can control the occurrence ofstreaking, and further, can control the coarsening of the pits. Theupper limit of the value of (D/E)×100 is on the order of 300, and evenif it is increased above this, the improvement in the effect is small,and the rolling costs increase by reducing the hot rolling temperature,and increasing the number of rolling passes, and the like.

Further, in the AlFe type intermetallic compound, a metastable phase ismore preferable than a stable phase (Al₃Fe), and in the composition ofthe intermetallic compound having a particle size of 0.1 μm or more, ifthe value of C/B is 0.35 or above when “C” is set as the number ofmetastable particles having an Fe/Al ratio of 0.6 or less, and “B” isset as the total number of particles of the intermetallic compound, itwas found that a large further improvement could be obtained. The upperlimit of the value of C/B is on the order of 0.80, and even if it isincreased above this, the improvement in the effects is small, and therolling costs increase by reducing the hot rolling temperature, and thenumber of rolling passes increases and the like.

Further, concerning the surface layer portion in which the intermetalliccompound particles are dispersed, in the case for use as a lithographicprinting plate, it is thought not to be a hindrance if the range of thedepth on the order of 50 μm from the outer surface contributes to theetching process to which it is subjected.

Below, the reasons for limiting the alloy components for the aluminumalloy plate for use as a lithographic printing plate specified by thepresent invention are explained. Further, in the specification of thepresent application, when the interval between the upper limit and thelower limit of the included amount is indicated by “to”, as long asthere is no particular indication, this means “or more”, and “or less”.Accordingly, as long as there is no other particular indication, 0.1 to0.6 means a range of 0.1 wt % or more, and 0.6 wt % or less.

“Fe”: 0.1 to 0.6 wt %

Fe is an element which has a large influence on the occurrence ofstreaking. If the included amount of Fe is less than 0.1 wt %, thecathode reaction is insufficient, and the streaking is intensified.Further, if the included amount of Fe exceeds 0.6 wt %, a coarseintermetallic compound readily forms, and further, the cathodesolubility decreases and streaking is intensified. Further, a preferablerange of the included amount of Fe is 0.2 to 0.5 wt %. A more preferablerange of the included amount of Fe is 0.2 to 0.4 wt %.

“Si”: 0.02 to 0.2 wt %

Si is an element which precipitates in the elemental aluminum andcontributes to making the crystal particles fine. If the included amountof Si is less than 0.02 wt %, it is necessary to use other metals havinga high degree of purity, and the cost will increase significantly.Further, if the included amount of Si exceeds 0.2 wt %, theintermetallic compound becomes coarse and the reactivity of the cathodedecreases, and there is a tendency to intensify the occurrence ofstreaking. A more preferable range for the included amount of Si is 0.05to 0.15 wt %.

“Zn”: 0.01 to 0.1 wt %

Zn is an element which has a large influence on the occurrence ofstreaking. With included amounts of Zn of less than 0.01%, the cathodesolubility insufficient, and it is difficult to obtain an improvedeffect on the streaking. Further, if the included amount of Zn exceeds0.1 wt %, the cathode solubility increases too much, and streaking isintensified. Further, a preferable range of the included amount of Zn is0.025 to 0.08 wt %, and a higher degree of uniformity of the roughenedsurface can be obtained.

“Ti”: 0.001 to 0.05 wt %

Ti is an element which makes the crystal particles fine, but if theamount of Ti is less than 0.001 wt %, this effect cannot be obtained.Further, if the amount of Ti exceeds 0.05 wt %, the coarse precipitatesincrease and the solubility of the cathode decreases, and there is atendency for streaking to be intensified. A more preferable range of theincluded amount of Ti is 0.005 to 0.02 wt %.

“Cu”: 0.001 to 0.02 wt %

Cu is an element which has a large influence on the occurrence ofstreaking. If the included amount of Cu is less than 0.001 wt %, thesolubility of the cathode is insufficient. Further, if the includedamount of Cu exceeds 0.02%, the cathode solubility decreases andstreaking is intensified. Further, a preferable range of the includedamount of Cu is 0.001 wt % or more, and less than 0.005 wt′ %. A morepreferable range of the included amount of Cu is 0.001 wt % or more, and0.004 wt % or less, to further increase the uniformity of the roughenedsurface.

“Mg”: 0.005 to 0.1 wt %

Mg is an element which has a large influence on the occurrence ofstreaking. If the included amount of the same is less than 0.005 wt %,the solubility of the cathode is insufficient, and the effect ofincreasing the strength is small, and to the contrary, if the includedamount exceeds 0.1%, the solubility of the cathode decreases, andstreaking is intensified. A more preferable range of the included amountof Mg is 0.021 wt % or more and 0.08 wt % or less, and further, in therange of 0.021 to 0.08 wt %, the uniformity of the roughened surfacebecomes even higher, and furthermore, the most more preferable range is0.021 wt % or above, and 0.04 wt % or less.

“Inevitable Impurities”

As impurities which can be included in the aluminum alloy plate of theinvention of the present application, Mn, Y, Sn, Zr, Ga, Ni, In and thelike are given as examples. The included amount of these impuritiesshould preferably be held to 0.03 wt % or less of each.

“The Relationship between the Included Amounts of Cu, Fe, Zn and Mg”

For the elements Cu, Fe, Zn and Mg, which have a large influence on theoccurrence of streaking, it is preferable that the relationship betweentheir included amounts satisfy the relationship equation0.15≧Zn+Mg−(Fe/10)−Cu. In particular, by increasing the amounts of Cuand Fe, the reactivity of the cathode is decreased. In response to thiseffect, it is necessary to suitably increase the amount of Zn. Further,in order to have a balance of increased strength and cathode solubilityin an appropriate range, it is necessary to adjust the included amountof Mn.

Further, of the many previously mentioned composition ranges, as anexample of the most preferred composition range, in wt %, Fe: 0.2 to0.4%; Si: 0.05 to 0.15%; Cu: 0.001 to 0.004%; Zn: 0.025 to 0.08%; Mg:0.02 to 0.04%; Ti: 0.001 to 0.05%, and the remainder Al and inevitableimpurities, can be given.

“Intermetallic Compound Particles”

The intermetallic compound particles form the starting points of theetching pits, and therefore, the size of the particles in the previouslymentioned dispersion layer wherein they are dispersed has an effect onthe properties of the pits which later form there. If this particle sizeis too small (equivalent-circle diameter less than 0.1 μm) the particlesare too fine and they do not sufficiently function as the startingpoints of etching pits, on the other hand, if the particle size is toolarge (equivalent-circle diameter exceeding 1.0 μm), the uniformity ofthe pits decreases. Accordingly, it is considered that the particle sizefor the intermetallic compound particles that has a suitable effect onpit formation is an equivalent-circle diameter of 0.1 μm to 1.0 μm.

Accordingly, in the surface direction, the higher the ratio of particleswithin this range of sizes among the intermetallic compound particles,the better the etchability that can be obtained. The surface directionmeans a surface direction parallel to the surface at a position at anarbitrary depth in the dispersion layer. Further, the presence ofintermetallic compound particles less than 0.1 μm can mostly be ignoredas starting points of pits, and therefore, it is possible to consideronly the intermetallic composition particles of 0.1 μm or greater, andspecify the ratios of the particles within the above range.

Concerning the intermetallic composition particles, it is preferable forthe value of A/B to be 0.2 or above in the case that A is the number ofparticles having an equivalent-circle diameter of 0.1 to 1.0 μm, and Bis the total number of particles of the intermetallic compoundparticles.

If the value of A/B is less than 0.2, the cathode solubility decreases,and streaking tends to be intensified. It is suitable for the value ofA/B to be 0.3 or above. The upper limit for A/B is on the order of 50,and if it exceeds this, the effect of improving the streaking is small.

Further, for the above mentioned intermetallic compound particles, it ispreferable for the value of (D/E)×100 to be 0.20 or above in the casethat D is the included amount of the intermetallic compound particleshaving an equivalent-circle particle diameter of 0.1 μm or more and lessthan 1.0 μm, and E is the included amount of particles with anequivalent-circle diameter of 1.0 μm or above.

Further, the particles having an effective action on the shape of thepits have a size of 0.1 to 1.0 μm. Particles having a size exceeding 1.0μm coarsen the pits. Accordingly, it is preferable to have a largeamount of particles of 0.1 to 1.0 μm. By making the value of (D/E)×100be 0.2 or above, the occurrence of streaking can be controlled, andfurther, the pit coarsening can be controlled. The upper limit of(D/E)×100 is on the order of 300, and if it is increased above this,improvements in the effects are small, and by making the hot rollingtemperature low, the number of rolling passes and the like increases andthe rolling costs increase.

“Metastable Phase Dispersion Layer”

Prior aluminum alloy plates for use as lithographic printing plates hada dispersion of stable phase of AlFe type intermetallic compound (Al₃Fe)particles, but those with a dispersion layer of a metastable phase werenot known. The present invention, unlike the prior art, comprises adispersion layer wherein a metastable phase of AlFe type intermetalliccompound particles are dispersed in the surface layer portion. Thismetastable phase is shown as a ratio of Al₄Fe, Al₅Fe, and Al₆Fe, orAl_(m)Fe (4<m<6). These are present individually or as a mixed phase.Further, the metastable phase particles are usually constituted only ofthis metastable intermetallic composition, however, it is alsoacceptable for a stable intermetallic composition to be mixed therewith.

The above described metastable intermetallic composition particles,compared to intermetallic compound particles of a stable phase, can morereadily be the starting point of pits, and effectively prevent theoccurrence of unetched portions and increase the dispersibility of thepits. Further, it is more effective for the m of Al_(m)Fe to be close to6.

“Dispersion Layer Depth”

The above dispersion layer is desirably formed from the surface to adepth of about 2 to 50 μm. In the production of an aluminum alloy platefor use as a lithographic printing plate, after rolling, and beforeelectrolytic etching, degreasing by caustic washing, or surface layerremoval by acid etching or mechanical polishing are carried out, andusually, in a chemical pretreatment, on the order of 0.1 to 2 μm, and inmechanical polishing, on the order of 0.1 to 5 μm is removed, andtherefore, the depth of the dispersion layer is shown in a state beforethe removal of the surface layer, and after rolling. On the other hand,even if the dispersion layer exceeds 50 μm, this does not contribute toan improvement in the electrolytic etching, and therefore, a depth ofthe dispersion layer on the order of 50 μm is thought to be sufficient.

“Crystal Particles”

It is preferable for the crystal particles (of the material surfacelayer) in a direction perpendicular to the rolling direction to have anaverage width of 60 μm or less, and with crystal particles larger thanthis, the cathode solubility decreases and there is a tendency tointensify the occurrence of streaking, and further, at the time ofbending, cracks can readily occur, and there is a great concern that therupture resistance will be reduced.

“Ratio of the Metastable Phase to the Stable Phase (in the DispersionLayer)”

In the dispersion layer, it is preferable to have dispersed thereinabout a certain ratio or above of intermetallic compound particles of ametastable phase which are excellent as starting points of pits.

Whether the intermetallic compound is a metastable phase or a stablephase is established by examining the ratio of the included amount of Feto the included amount of Al in the particles. In the particles, in somecases the stable phase and the metastable phase can exist in contactwith each other, but in this case it is possible to obtain sufficientfunction as a starting point of pits in the same way as for particles ofa single metastable phase, and therefore, these can be considered as ifthey were a metastable phase. The above ratio can be shown in terms ofthe (Fe amount)/(Al amount) of each particle, and those particles forwhich this exceeds 0.6 ((Fe amount)/(Al amount)>0.6 . . . Eq. A₁) can beconsidered as stable phase particles, and those particles for which thisis 0.6 or less ((Fe amount)/(Al amount)≦0.6 . . . Eq. A₂) can beconsidered a metastable phase.

In a composition of an intermetallic compound with a particle diameterof 0.1 μm or above, wherein the number of the metastable phase particleswhere the (Fe amount)/(Al amount) is 0.6 or less is C, and the totalnumber of intermetallic compound particles is B, by making the value ofC/B is 0.35 or above, it is possible to obtain improved effects of thedispersion of the metastable phase particles.

Further, it is not particularly necessary to determine an upper limit ofthe ratio of the metastable particles, but according to the constraintsof the production method, it is usual for C/B to be on the order of 0.8,and even if it is higher than this, the improvement in effects is small,and by making the rolling temperature low, the costs increase by makingthe number of rolling passes increase and the like.

An aluminum alloy plate having the above composition and with the aboveintermetallic compound particles dispersed in its surface layer, can beproduced by a method combining well known and usual production methodsby changing one part of the same to specified conditions.

In the usual production method for the aluminum alloy, after makingingots with the target composition, a homogenezation process is carriedout with the objective of eliminating segregation and the like of thecomponents, and at this stage, the metastable phase is mostly no longerpresent. Further, in the heat treatment process (soaking treatment)before hot rolling, if there is sufficient heating, what little remainsof the metastable phase is eliminated. Accordingly, in the productionprocess, by carrying out suitable heat management, it is possible toobtain an aluminum alloy plate in a state wherein metastable particlesare sufficiently dispersed.

Below, a process for producing one example of the aluminum alloy plateof the present embodiments will be explained.

First, the aluminum alloy of the present embodiment can be made intoingots by a usual method, and can be obtained for example, by adjustingthe components and mixing the raw materials to form the targetcomposition ratio, and casting. After this, in usual processes,homogenization of the components is done by carrying out ahomogenization treatment at a temperature exceeding 550° C., but in thepresent embodiment, in order to obtain the metastable phase, thehomogenization treatment is omitted, or the homogenization is carriedout at a temperature of 550° C. or less, and after this, in the hotrolling process, rolling is carried out at a temperature of 550° C. orless, and then cold rolling is carried out to obtain an aluminum alloyplate of the desired thickness. Further, in the cold rolling process, itwould not be problematic to subject the plate to an annealing process.

The aluminum alloy plate obtained in this way, before coating thephotosensitizer, is subjected to surface washing by a caustic washingtreatment using caustic soda or the like.

The aluminum alloy plate whose surface has been washed is subjected to asurface roughening treatment in order to roughen its surface, and thissurface roughening treatment is done by electrolytic etching. In thiselectrolytic etching treatment, as the aluminum alloy plate is passedthrough the rolls, it is electrolytically treated by applying analternating voltage to the electrodes. In this process, due to therelationship between the speed of passing through the rolls and thefrequency of the alternating current, the degree of whitening at thecathode point and the anode point can change greatly, and in thedirection perpendicular to the conveying direction (the direction alongthe width direction) of an aluminum alloy plate subjected to a conveyingelectrolytic etching treatment, streaking can easily occur.

On this point, for the aluminum alloy plate of the present embodiment,if the alloy composition is adjusted according to the previousdisclosures, a balance of the electrolytic conditions between the anodepoint and the cathode point can be obtained, and therefore, streaking atthe time of the roughening treatment by electrolysis does not readilyoccur. Further, the size, number, and composition of the intermetalliccompound particles, which can form the starting points for theelectrolysis as stated before, are controlled so as to be within adefined range, and therefore, the balance of the electrolysis conditionsbetween the cathode point and the anode point can be further improved,and the occurrence of streaking can be controlled.

The photosensitive layer provided on the aluminum alloy plate of thepresent invention can be obtained by coating and drying a photosensitiveliquid comprising a photosensitive composition. As the photosensitiveliquid, it is possible to use one which has been used in the productionof prior photosensitive lithographic printing plates.

As such a photosensitive liquid, (1) a positive type photosensitivecomposition comprising an o-quinone diazide compound; (2) a negativetype photosensitive composition comprising a diazonium compound; (3) anegative type photosensitive composition comprising a compositioncomprising an addition polymerizable unsaturated group and a photopolymerization initiator; (4) a positive type laser photosensitivecompound comprising an alkali soluble resin and a photothermalconversion agent; and (5) a negative type photosensitive compoundcomprising an alkali soluble resin, an acid generating agent, acrosslinking agent and a photothermal conversion agent; or the like;dissolved or dispersed in an organic solvent, are given as examples.

The o-quinone diazide compound in the positive type photosensitivecomposition comprising an o-quinone diazide compound is a compositioncomprising at least one o-quinone diazide group, and it is preferablyone which has increased solubility in an alkaki aqueous solution as aresult of active rays. Many compounds having a variety of structures areknown as such compounds, for example, those disclosed in J. Kosar,“Light Sensitive Systems” (John Wiley & Sons, Inc., published in 1965),pp. 336-352. As an o-quinone diazide compound, in particular, sulphoneesters of o-quinone diazides or o-naphthoauinone diazides and a varietyof hydroxyl compounds are suitable.

In the (1) positive type photosensitive composition comprising ano-quinone diazide compound, it is possible to use as a binder resin aresin which is insoluble in water, but soluble in alkali aqueoussolutions (below referred to as an alkali soluble resin), and this canimprove the developing characteristics, the durability, solventresistance, chemical resistance and the like. As the alkali solubleresin, for example, a novolak type resin or a resol type resin such as aphenol.formaldehyde resin, a cresol.formaldehyde resin, aphenol.cresol.formaldehyde cocondensed resin, or an acrylic type resincomprising one or more monomers comprising an acidic group, such aspolyhydroxystyrene, polyhalogenated hydroxystyrene, N-(4-hydroxyphenyl)methacrylic amide, hydroquinone monomethacrylate, N-(sulfamoylphenyl)methacrylic amide, N-phenyl sulfonyl methacrylic amide, N-phenylsulphonyl maleimide, acrylic acid, methacrylic acid and the like, andthe like can be given as examples.

Further, it is possible to add various additives to the (1) positivetype photosensitive composition comprising an o-quinone diazidecompound, as necessary, a cyclic acid anhydride in order to increase itssensitivity, a print out agent in order to obtain an optical imageimmediately after exposure, a dye as an image coloring agent, otherfillers, various types of resin comprising hydrophobic groups in orderto improve the ink adhesiveness of the image, a plasticizer in order toimprove the flexibility of the film, and the like.

As the diazonium compound in the (2) negative type photosensitivecomposition comprising a diazonium compound, for example, diazo resinsrepresented by salts of condensates of diazodiarylamine and activecarbonyl compounds, and those that have light sensitivity and that areinsoluble in water but soluble in organic solvents are preferable. Asparticularly suitable diazo resins, for example, organic salts, andinorganic salts of condensates of 4-diazodiphenylamine,4-diazo-3-methylphenylamine, 4-diazo-4′-methyldiphenylamine,4-diazo-3′-methyldiphenylamine, 4-diazo-4′-methoxydiphenylamine,4-diazo-3-methoxydiphenylamine, formaldehyde, paraformaldehyde,acetaldehyde, benzaldehyde, 4,4′-bis-methoxymethyl diphenylether and thelike can be listed. Further, the (2) negative type photosensitivecomposition comprising a diazonium compound is usually used with abinder resin. As such a binder resin, for example, acrylic resin,polyamide resin, polyester resin, epoxy resin, polyacetal resin,polystyrene resin, novolak resin, and the like can be listed. Further,in order to improve the performance, well known additives, for example,thermal polymerization inhibitors, dyes, pigments, plasticizers,stabilizing agents, and the like can be added.

As the (3) negative type photosensitive composition comprising acompound comprising an addition polymerizable unsaturated group, and aphoto polymerization initiator, there are the compositions comprisingthe compounds comprising an addition polymerizable unsaturated grouphaving two or more terminal ethyl groups, and a photopolymerizationinitiator, disclosed in U.S. Pat. No. 2,760,863, U.S. Pat. No.3,060,023, and Japanese Unexamined Patent Application, First PublicationNo. Sho 62-121448. The compound comprising an addition polymerizableunsaturated group is a monomer or oligomer comprising at least one andpreferably two or more ethylenic unsaturated addition polymerizablegroups per molecule, and having a boiling point of 100° C. or more. Asthe photopolymerization initiator, the α-carbonyl compounds disclosed inU.S. Pat. No. 2,367,661, the acyloin ether disclosed in U.S. Pat. No.2,448,828, the α-hydrocarbon substituted aromatic acyloin compounddisclosed in U.S. Pat. No. 2,722,512, the polyquinone compoundsdisclosed in U.S. Pat. No. 3,046,127, the triarylbiimidazole.P-aminophenylketone combination disclosed in U.S. Pat. No. 3,459,367,the trihalomethyl-s-triazine type compound disclosed in U.S. Pat. No.4,239,850, the oxadiazole type compound disclosed in U.S. Pat. No.4,212,970, the acridine and phenazine compounds disclosed in U.S. Pat.No. 3,751,259, the benzothiazole compound disclosed in JapaneseUnexamined Patent Application, First Publication No. Sho 51-48516 andthe like can be listed as examples. Further, to the (3) negative typephotosensitive composition comprising a compound comprising an additionpolymerizable unsaturated group and a photo polymerization initiator, itis possible to add a binder resin and well-known additives, such as athermal polymerization inhibitor, pigment, dye, plasticizer, stabilizingagent, and the like.

As the alkali soluble resin of the (4) positive type laserphotosensitive composion comprising an alkali soluble resin and aphotothermal conversion agent, for example, the same alkali solubleresin used in the (1) positive type photosensitive compositioncomprising an o-quinone diazide compound can be used. The photothermalconversion agent is a substance which absorbs light and generates heat.As such a substance, a variety of pigments and dyes can be given asexamples. As a pigment, commercially available pigments, and thosedisclosed in color index handbooks, such as the “Japan Pigment SocietyNewest Pigment Handbook, Published 1977”, the “Newest PigmentApplication Techniques” (CMC, published 1984), and the like can be used.As dyes, common and well known dyes can be used, for example, thosedisclosed in the “Dye Handbook” (Organic Synthetic Chemistry Society,published in the year Showa 45 (1970)), “Coloring Material EngineeringHandbook” (Coloring Material Society, Asahikaura Booksellers, published1989), “Technology and Markets of Industrial Colorants” (CMC, published1983), and “Chemical Handbook: Applied Chemistry” (Japan ChemicalSociety, Maruzen Bookseller, published 1986). In particular, thosehaving an absorbance region in the infrared region with wavelengths of600 nm or above, preferably 750˜1200 nm, which show a photothermalconversion function of these wavelengths are preferable.

As the alkali soluble resin and photothermal conversion agent of the (5)negative type laser photosensitive composition comprising an alkalisoluble resin, an acid generating agent, a crosslinking agent and aphotothermal conversion agent, it is possible to use the same alkalisoluble resin and photothermal conversion agent as used in the (4)positive type laser photosensitive composition comprising an alkalisoluble resin and a photothermal conversion agent. As the acidgenerating agent, well known onium salts such as ammonium salts,phosphonium salts, iodinium salts, sulphonium salts, selenium salts andthe like, organic halogen compounds, photoacid generators comprising ao-nitrobenzoyl type protecting group, disulphonated compounds and thelike can be given as examples. In particular, from the point that a highdegree of sensitivity can be obtained, trihaloalkyl compounds anddiazonium salt compounds can suitably be used. The crosslinking agentcrosslinks as a result of the catalyzing action of the acid generated bythe acid generating agent, and as long as it insolubilizes, it is notparticularly limited. As such a crosslinking agent, amino compoundscomprising at least two methylol groups, alkoxymethyl groups,acetoxymethyl groups and the like, can be given as examples.Specifically, melamine derivatives such as methoxymethylated melamine,benzoguanamine derivatives, glycol uryl derivatives and the like; urearesin derivatives; resol resins and the like can be given as examples.

As the organic solvent wherein these photosensitive compositions aredissolved or dispersed, any well known and common one can be used. Amongthese, those having boiling points in the range of 40° C. to 200° C.,and in particular, from 60° C. to 160° C. are selected for theiradvantages at the time of drying. As the organic solvent, the alcoholclass, the ketone class, the hydrocarbon class, acetic ester class, theether class, the polyol class and its derivatives, dimethylsulphoxide,N,N-dimethylformamide, methyl lactate, ethyl lactate and the like aregiven as examples.

As the coating method for the photosensitive composition, for example,the methods of roll coating, dip coating, air knife coating, gravurecoating, gravure offset coating, hopper coating, blade coating, wiredcoating, spray coating and the like can be used. The amount of coatedphotosensitive composition is suitably in the range of 10 ml/m² to 100ml/m². The drying of the photosensitive composition coated onto thesupport body is usually carried out by heated air. The heating issuitably in the range of 30° C. to 200° C., in particular 40° C. to 140°C. For the heating temperature, in addition to a method of holding afixed temperature during heating, a method of increasing the temperaturestepwise can be employed. Further, by dehumidifying the drying air,preferable results can be obtained. The heated air is suitably suppliedat a rate of 0.1 m/sec to 30 m/sec, in particular 0.5 m/sec to 20 m/secwith respect to the coating surface. The coating amount of thephotosensitive compound usually has a dried weight in the range of about0.5 to about 5 g/m².

Below, the present invention is explained based on the embodiments, butit is clear that the present invention is not limited to the belowembodiments.

FIG. 1 shows one example constitution of the lithographic printing plate3 formed by coating a photosensitive layer 2 on the aluminum alloy plate1 of the present invention. The surface of an aluminum alloy plate as inthis example is subjected to surface treatments such as a surfaceroughening treatment (graining) by electrolytic etching and anodicoxidation treatment and with the surface maintained in this way, thelithographic printing plate 3 is coated with a photosensitive layer 2.

“Manufacturing of the Aluminum Alloy Plate”

For a slag obtained by adjusting the raw materials to obtain the targetcomposition ratio and casting, a soaking treatment was carried outwithout carrying out a homogenization treatment, and an aluminum alloyplate with a thickness of 6 mm was obtained by hot rolling. Further,this aluminum alloy plate is rolled to a thickness of 0.3 mm by coldworking to obtain aluminum alloy test samples.

Further, from the above slag, test samples were obtained by carrying outa homogenization process at a temperature in the range of 450° C. to600° C., a soaking process at 400° C. to 600° C. and hot rolling to athickness of 6 mm, and further rolling by a cold rolling process to athickness of 0.30 mm.

The obtained aluminum alloy plates were degreased in an aqueous solutionof sodium hydroxide, and were immersed in a 2% aqueous solution ofhydrochloric acid at room temperature, and an AC current of 50 Hz, 100A/dm² was applied between the aluminum alloy plate and carbonelectrodes, and further, an electrolytic etching treatment was carriedout by moving the aluminum alloy plate at a speed of 20 m/min withrespect to the electrodes. After this treatment, the aluminum alloyplate was washed with water, washed for 1 min in 10% sulfuric acid atroom temperature, neutralized, further washed with water and dried. Inthe above production process, a plurality of test samples weremanufactured with variously adjusted compositions of the aluminumplates, and a plurality of test samples were manufactured with variousdifferent values of the included amounts of Cu, Fe, Mg, and Zn with therelationship “0.15≧Zn+Mg−(Fe/10)−Cu”, and further, measurements of thenumbers of particles, included amount and crystal particle size of theintermetallic compounds were carried out, and the measured value of theproportion [C]/[B] of the metastable phase of the composition of theintermetallic compound, the streaking conditions, and the ruptureresistance and printing durability were studied.

In the results, the results for the test samples of the presentinvention are shown in Table 2, and the results for the test samplesoutside the range of the present invention are shown in Table 4.

Further, the surface of the obtained aluminum alloy plate was visuallyinspected, and those on which streaking was not observed at all areindicated with ⊚, those for which some streaking was observed areindicated with ◯, and those for which streaking was clearly observed areindicated with X in Tables 3 and 5 disclosed below.

For the particle numbers of the intermetallic compound, using a scanningelectron microscope, the electron reflection image of the surface of thealuminum alloy plate was observed at a magnification of 3000 times.Observation was carried out at 20 random locations, and the number ofparticles with an equivalent-circle diameter of 0.1 μm or more and theirequivalent-circle diameters were measured. Further, by EPMA, the ratioof Fe and Al of each intermetallic compound particle was measured, andis shown in Tables 3 and 5.

Concerning the rupture resistance, as substitute test samples aftersubjecting the previous aluminum alloy plates having a thickness of 0.30mm to the above electrolytic etching, a portion corresponding to theanode position having streaking as the front was bent to an interiorangle of 20°, and this bent portion was observed by an opticalmicroscope, and in Tables 3 and 5, those samples where cracks wereobserved are evaluated as X, and those where cracks were not observedare evaluated as ◯.

Concerning the printing durability, an aluminum plate subjected to theabove electrolytic etching, had a sulphuric alumite coating of 2.7 g/m²formed thereon at 2 A/dm² in a 20% sulphuric acid solution. This anodicoxidized plate, after a hydrophilization treatment, was washed withwater and dried to obtain an aluminum support body.

Then the coating liquid of the photosensitive composition in thefollowing Table 1 is coated at low speed with a roll coater onto thealuminum support body, and dried for 3 min at 100° C. to obtain aphotosensitive lithographic printing plate. The amount of the drycoating was 2.0 g/m². A solid or halftone dot negative image film, a0.15 step step wedge glued to the obtained photosensitive lithographicprinting plate. Using a 2 kW output metal halide lamp provided at adistance of 1 m from the photosensitive lithographic printing plate, thephotosensitive lithographic printing plate was exposed with an exposuretime to make the sensitivity a 4 step. After this, using a PD-912automatic developing machine manufactured by Dainippon Screen Mfg. Co.,Ltd., and an ND-1 developing solution for negative printing manufacturedby Kodak Polychrome Graphics Japan Ltd, (dilution ratio 1:3), theexposed photosensitive lithographic printing plate was subjected to adeveloping treatment for 20 sec at 30° C. and coated with NF-2 gummanufactured by Kodak Polychrome Graphics Japan Ltd. Printing wascarried out using the obtained lithographic printing plate. After it wasattached to the print cylinder and 300,000 prints were made, the imagefading was observed. Test samples for which image fading were found areindicated by X, and those for which it was not found are indicated by ∘in Tables 3 and 5.

Concerning the uniformity of the roughened surface, for the abovesamples, an electrolytic etching treatment was carried out under theconditions of 30 sec with a current of 60 A/dm² at a frequency of 50 Hz,at a solution temperature of 25° C. in a 2% hydrochloric acid solution,and after the treatment, their surfaces were observed by SEM at amagnification of 500×, and the test samples where the large pits havingan equivalent-circle diameter exceeding 10 μm have a surface area ratioof 5% or more with respect to the total number of pits are indicated inTables 3 and 5 with X, those samples where they are present from 2% ormore to less than 5% are shown as Δ in the tables, and those where thesamples are less than 2% are indicated with ◯.

To obtain the value of (D/E)×100, approximately 1 g of an aluminum testsample was dissolved in 100 g of phenol at 180° C., 100 g of benzylalcohol was added and after reheating to 180° C., filtered with amembrane filter with a pore size of 1.0 μm, and particles with a size of1.0 μm or more were trapped, and after washing with benzyl alcohol, theweight of the dried trapped particles was measured as “E”. The filteredliquid was filtered with a 0.1 μm membrane filter to trap the particlesof 0.1 μm and above and less than 1.0 μm, and after these were washedwith benzyl alcohol, the weight of the dried trapped particles wasmeasured as “D”. Their ratio was taken to calculate the value of(D/E)×100. The results are shown in Tables 3 and 5.

TABLE 1 Coating Liquid of the Photosensitive Composition Units: g2-hydroxyethylmethacrylate copolymer (disclosed in Example 1 1.75 ofJapanese Unexamined Patent Application, First Publication No. 50-118802)2-methoxy-4-hydroxy-5-benzoylbenzene sulphonic acid salt of 0.20condensate of p-diazodiphenylamine and formaldehyde Oil blue #603 [mfg.by Orient Chemical Industries, Ltd.] 0.05 Megaface F-177 [fluorinatedsurfactant mfg. by Dainippon Ink 0.015 and Chemicals, Inc.] Methylglycol28.0 methyl cellosolve acetate 20.0

TABLE 2 Relational Formula Zn + Test Mg − Sample Chemical Components(Fe/10) − No. Fe Si Cu Zn Mg Ti Cu  1 0.1  0.02 0.003 0.05 0.030 0.010.067  2 0.3 0.1 0.003 0.05 0.032 0.01 0.047  3 0.6 0.1 0.003 0.03 0.0300.01 −0.003  4 0.3 0.2 0.003 0.03 0.033 0.01 0.027  5 0.3 0.1 0.001 0.030.032 0.01 0.029  6 0.3 0.1 0.02  0.03 0.030 0.01 0.01  7 0.3 0.1 0.0030.01 0.031 0.01 0.007  8 0.3 0.1 0.003 0.10 0.030 0.01 0.097  9 0.3 0.10.003 0.03 0.005 0.01 0.002 10 0.3 0.1 0.003 0.03 0.100 0.01 0.097 110.3 0.1 0.003 0.03 0.031  0.001 0.027 12 0.3 0.1 0.003 0.03 0.030 0.050.027 13 0.1 0.1 0.002 0.08 0.080 0.01 0.148 14 0.3 0.1 0.003 0.03 0.0300.01 0.027 15 0.3 0.1 0.003 0.03 0.031 0.01 0.027 16 0.3 0.1 0.003 0.030.030 0.01 0.027 17 0.3 0.1 0.006 0.03 0.033 0.01 0.027 17a 0.3 0.10.004 0.03 0.030 0.01 0.025 17b 0.3 0.1 0.003 0.03 0.030 0.01 0.026 17c0.3 0.1 0.003 0.03 0.020 0.01 0.017 17d 0.3 0.1 0.003 0.03 0.021 0.010.018 17e 0.3 0.1 0.003 0.03 0.080 0.01 0.107 17f 0.3 0.1 0.003  0.0230.032 0.01 0.022 17g 0.3 0.1 0.003  0.025 0.035 0.01 0.024 17h 0.3 0.10.005 0.03 0.030 0.01 0.025 17i 0.3 0.1 0.003 0.08 0.030 0.01 0.077

TABLE 3 Crystal Rupture Test Particle Particle resistance/ RoughenedSample Diameter Number Metastable Homogenization Printing Surface No.(μm) A/B Phase C/B Treatment Streaking durability (D/E) × 100 Uniformity 1 46  0.38 0.37 550° C. × 3 hr ⊚ ◯/◯ 0.304 ◯  2 46 0.3 0.38 530° C. × 3hr ⊚ ◯/◯ 0.240 ◯  3 46  0.21 0.45 none ⊚ ◯/◯ 0.168 ◯  4 46 0.3 0.36 none⊚ ◯/◯ 0.240 ◯  5 46 0.3 0.36 none ⊚ ◯/◯ 0.240 ◯  6 46 0.3 0.36 none ⊚◯/◯ 0.240 Δ  7 46 0.3 0.37 510° C. × 3 hr ⊚ ◯/◯ 0.240 Δ  8 46 0.3 0.38none ⊚ ◯/◯ 0.240 Δ  9 46 0.3 0.40 none ⊚ ◯/◯ 0.240 Δ 10 46 0.3 0.39 500°C. × 5 hr ⊚ ◯/◯ 0.240 ◯ 11 46 0.3 0.36 none ⊚ ◯/◯ 0.240 ◯ 12 46 0.3 0.36none ⊚ ◯/◯ 0.240 ◯ 13 46 0.3 0.37 530° C. × 3 hr ⊚ ◯/◯ 0.240 ◯ 14 60 0.30.36 none ⊚ ◯/◯ 0.240 ◯ 15 46  0.18 0.35 none ◯ ◯/◯ 0.144 ◯ 16 46 0.30.33 560° C. × 3 hr ◯ ◯/◯ 0.240 ◯ 17 46 0.3 0.11 580° C. × 1 hr ◯ ◯/◯0.144 ◯ 17a 46 0.3 0.36 none ◯ ◯/◯ 0.240 Δ 17b 46 0.3 0.35 none ⊚ ◯/◯0.240 ◯ 17c 46 0.3 0.36 none ◯ ◯/◯ 0.240 Δ 17d 46 0.3 0.37 none ◯ ◯/◯0.241 ◯ 17e 46 0.3 0.38 510° C. × 3 hr ⊚ ◯/◯ 0.241 Δ 17f 46 0.3 0.37510° C. × 3 hr ⊚ ◯/◯ 0.240 Δ 17g 46 0.3 0.36 510° C. × 3 hr ⊚ ◯/◯ 0.242◯ 17h 46 0.3 0.37 none ◯ ◯/◯ 0.240 ◯ 17i 46 0.3 0.38 none ⊚ ◯/◯ 0.241 ◯

TABLE 4 Relational Formula Zn + Test Mg − Sample Chemical Components(Fe/10) − No. Fe Si Cu Zn Mg Ti Cu 18  0.04  0.02 0.005 0.05 0.030 0.010.071 19 0.7  0.02 0.005 0.05 0.030 0.01 0.005 20 0.3  0.28 0.005 0.040.021 0.01 0.025 21 0.3 0.2  0.0004 0.03 0.022 0.01  0.0196 22 0.3 0.10.026 0.03 0.021 0.01 −0.006   23 0.3 0.1 0.005  0.003 0.023 0.01−0.012   24 0.3 0.1 0.005 0.16 0.021 0.01 0.145 25 0.3 0.1 0.005 0.050.004 0.01 0.019 26 0.3 0.1 0.005 0.03 0.160 0.01 0.155 27 0.3 0.1 0.0050.03 0.030  0.0004 0.025 28 0.3 0.1 0.005 0.03 0.021 0.06 0.025 29 0.10.1 0.001 0.1  0.100 0.01 0.189

TABLE 5 Crystal Rupture Test Particle Particle resistance/ RoughenedSample Diameter Number Metastable Homogenization Printing Surface No.(μm) A/B Phase C/B Treatment Streaking Durability (D/E) × 100 Uniformity18 61 0.43 0.35 550° C. × 2 hr X X/X 0.344 Δ 19 41 0.21 0.51 None X X/X0.168 Δ 20 38 0.38 0.39 530° C. × 1 hr X X/X 0.304 Δ 21 45 0.3 0.35 NoneX X/X 0.240 ◯ 22 46 0.25 0.38 None X X/X 0.200 Δ 23 43 0.28 0.36 None XX/X 0.224 Δ 24 46 0.3 0.38 510° C. × 2 hr X X/X 0.240 Δ 25 43 0.28 0.37None ⊚ X/X 0.224 X 26 45 0.29 0.38 None X X/X 0.232 Δ 27 63 0.3 0.39500° C. × 5 hr X X/X 0.240 Δ 28 37 0.55 0.40 None X X/X 0.240 Δ 29 460.31 0.36 None X X/X 0.248 Δ

In sample No. 1 of Table 2, the included amounts of Fe and Si are thelower limits of the range of the present invention, and the otherconditions are within the range of the present invention, and accordingto the results shown in Table 3, the occurrence of streaking was notobserved, and also from the viewpoint of rupture resistance and printingdurability, problems did not occur. In contrast, sample No. 19 of Table4 has an increased included amount of Fe, and Sample No. 20 has anincreased included amount of Si, and according to the results shown inTable 5, streaking did occur, and problems also occurred from theviewpoint of rupture resistance and printing durability.

In sample No. 2 of Table 2, the included amounts of Fe, Si, Cu, Zn andTi, the value of the relationship expression, the crystal particle size,the value of A/B, and the value of C/B are all within the range of thepresent invention, and as shown in Table 3, the occurrence of streakingwas not observed, and also from the viewpoint of both rupture resistanceand printing durability, problems did not occur.

In sample No. 3 of Table 2, the included amount of Fe is the upper limitof the present invention, in sample No. 4 the included amount of Si isthe upper limit, in sample No. 5 the included amount of Cu is the lowerlimit, in sample No. 6 the included amount of Cu is the upper limit, insample No. 7 the included amount of Zn is the lower limit, in sample No.8 the included amount of Zn is the upper limit, and as shown in Table 3,the occurrence of streaking was not observed, and from the viewpoint ofrupture resistance and printing durability, problems did not occur.

In sample No. 9 of Table 2, the included amount of Mg is the lowerlimit, in sample No. 10 the included amount of Mg is the upper limit, insample No. 11 the included amount of Ti is the lower limit, in sampleNo. 12 the included amount of Ti is the upper limit. In all of thesesamples, the occurrence of streaking was not observed, and from theviewpoint of rupture resistance and printing durability, problems didnot occur.

Further, in sample No. 6 of Table 2, the included amount of Cu is 0.02wt %, and therefore, the roughened surface uniformity is Δ, in sampleNo. 7 the included amount of Zn is 0.01 wt %, and therefore, theroughened surface uniformity is Δ, and in sample No. 9 the includedamount of Mg is 0.005 wt %, and therefore, the roughened surfaceuniformity is Δ.

Sample No. 13 of Table 2 is within the range of the composition of thepresent invention, and sample No. 14, as shown in Table 3, has a crystalparticle size of the upper limit of 60 μm, and the occurrence ofstreaking was not observed, and from the viewpoint of rupture resistanceand printing durability, problems did not occur.

Sample No. 15 of Table 2 is within the composition range of the presentinvention, but the number of particles of the intermetallic compound isoutside of the range of 0.2 or above of the present invention. In sampleNo. 15, as shown in Table 3, the occurrence of streaking was slight, andthere was no problem concerning rupture resistance and printingdurability. Sample No. 16 of Table 2 is within the composition range ofthe present invention, but the ratio of C/B is outside of the range of0.35 or above of the present invention, and further, the homogenizationtreatment was carried out at a temperature exceeding the upper limit of550° C. of the preferable homogenization treatment of the presentinvention. For this sample No. 16 as shown in Table 3, the occurrence ofstreaking was slight, and there was no problem concerning ruptureresistance and durability.

Sample No. 17 of Table 2 has a C/B ratio outside of the range of thepresent invention of 0.35 and above, and further had a homogenizationtreatment at a temperature exceeding 550° C. which is the preferablehomogenization treatment of the present invention. For this sample No.17, as shown in Table 3, there was a slight occurrence of streaking, butthere were no problems concerning rupture resistance and printingdurability.

Sample No. 17 a of Table 2 has a larger amount of Cu (Cu 0.006%) thanthe more preferable range of the included amount of Cu of the presentinvention (0.005% or less), and as a result there was a slightoccurrence of streaking, and the roughened surface uniformity had aresult of Δ.

Sample No. 17 b of Table 2 has an included amount of Cu within thepreferable range of the present invention (0.004 wt %, less than 0.005wt %) and showed the favorable result that streaking was not observed.

Sample No. 17 c of Table 2 has a lower amount of Mg (Mg 0.020%) than themore preferable range of the included amount of Mg of the presentinvention (Mg 0.021 or above), and as a result there was a slightoccurrence of streaking, and the roughened surface uniformity had aresult of Δ.

Next, concerning the roughened surface uniformity, sample No. 17 c forwhich Mg is outside of the preferable range has a roughened surfaceuniformity of Δ, but for sample No. 17 d, which is inside the preferablerange, it was ◯. Sample No. 10 with an included amount of Mg of 0.001 wt% was ◯, sample No. 17 e with an included amount of Mg. of 0.0080 wt %was Δ. Next, sample No. 17 f included 0.023 wt % of Zn, which is outsidethe preferable range of the present invention, and the roughened surfaceuniformity had a result of Δ, sample No. 17 e which has an includedamount of Zn of 0.025 wt %, within the preferable range, has a roughenedsurface uniformity of ◯. Further, sample No. 8 has a greater amount ofZn than the preferable range and therefore the roughened surfaceuniformity is Δ, and sample No. 17 i which is within the preferablerange has a roughened surface uniformity of Δ.

Next, concerning the preferable range of Cu, sample No. 17 a has anincluded amount of 0.006 wt % which is greater than the preferable rangeand therefore the roughened surface uniformity was Δ, sample No. 17 hhas the preferable upper limit of the preferable range of 0.005 wt % andwas ◯. Further, from a comparison of the streaking of sample No. 17 band sample No. 17 h, it can be judged that it is more preferable for theincluded amount of Cu to be 0.004 wt % or less.

Sample No. 18 of Table 4 has an included amount of Fe which is lowerthan the range of the present invention, and as shown in Table 5, thissample has a crystal particle diameter exceeding the range of thepresent invention and streaking occurred, and problems also occurredconcerning rupture resistance and printing durability. Sample No. 19 ofTable 2 has an included amount of Fe which is greater than the range ofthe present invention, and streaking occurred, and problems alsooccurred concerning rupture resistance and printing durability.

Sample No. 20 of Table 4 has an included amount of Si which is greaterthan the range of the present invention, and as shown in Table 5,streaking occurred, and problems also occurred rupture resistance andprinting durability.

Sample No. 21 of Table 4 has an included amount of Cu which is below therange of the present invention, and as shown in Table 5, streakingoccurred, and problems also occurred concerning rupture resistance andprinting durability.

Sample No. 22 of Table 4 has an included amount of Cu which is above therange of the present invention, and as shown in Table 5, streakingoccurred, and problems also occurred concerning rupture resistance andprinting durability.

Sample No. 23 of Table 4 has an included amount of Zn which is below therange of the present invention, and as shown in Table 5, streakingoccurred, and problems also occurred concerning rupture resistance andprinting durability.

Sample No. 24 of Table 4 has an included amount of Zn which is above therange of the present invention, and as shown in Table 5, streakingoccurred, and problems also occurred concerning rupture resistance andprinting durability.

Sample No. 25 of Table 4 has an included amount of Mg which is below thepreferable range of the present invention, and as shown in Table 5,there was no occurrence of streaking, but problems occurred concerningrupture resistance and printing durability.

Sample No. 26 of Table 4 has an included amount of Mg which is above thepreferable range of the present invention, and as shown in Table 5,streaking occurred, and problems also occurred concerning ruptureresistance and printing durability.

Sample No. 27 of Table 4 has an included amount of Ti which is below thepreferable range of the present invention, and sample No. 28 has anincluded amount of Ti which is above the preferable range of the presentinvention, and as shown in Table 5, streaking occurred, and problemsalso occurred concerning rupture resistance and printing durability.

Sample No. 29 of Table 4 has an elemental composition within the rangeof the present invention, however, the value of the relationship formulais above the range of the present invention, and as shown in Table 5,streaking occurred, and there were also problems with rupture resistanceand printing durability.

1. An aluminum alloy plate for use as a lithographic printing plate, thealuminum alloy plate comprising, in wt %, Fe: 0.1 to 0.6%; Si: 0.02 to0.2%; Cu: 0.001 to 0.003%; Zn: 0.01 to 0.1%; Mg: 0.021 to 0.1%; Ti:0.001 to 0.05%, and the remainder aluminum and inevitable impurities,and the aluminum alloy plate comprising a plurality of AlFeintermetallic compound particles in its metal structure, and wherein: anaverage value of the crystal particle size is 60 μm or less in adirection perpendicular to the rolling direction; the included amountsof Cu, Fe, Zn, and Mg satisfy the relationship:0.15≧(Zn+Mg−(Fe/10)−Cu); the composition of said AlFe intermetalliccompound particles having a particle size of 0.1 μm or above, the valueof C/B is 0.35 or above when C is a number of AlFe metastable phaseintermetallic compound particles having a ratio of Fe/Al of 0.6 or less,and B is a total number of AlFe intermetallic compound particles; and avalue of A/B is 0.2 or above in the case that in said AlFe intermetalliccompound particles, A is a number of AlFe intermetallic compoundparticles having an equivalent-circle diameter of 0.1 to 1.0 μm, and Bis a total number of AlFe intermetallic compound particles having aparticle size of 0.1 or above.
 2. The aluminum alloy plate for use as alithographic printing plate of claim 1 wherein, a value of (D/E)×100 is0.20 or above in the case that in said AlFe intermetallic compoundparticles, D is an included amount of AlFe intermetallic compoundparticles having an equivalent circle diameter of 0.1 μm or above andless than 1.0 μm, and E is an included amount of AlFe intermetalliccompound particles above 1.0 μm.
 3. The aluminum alloy plate for use asa lithographic printing plate of claim 1, wherein the plate comprises0.03 wt % of less of each of the impurities Mn, Y, Sn, Zr, Ga, Ni, andIn.
 4. The aluminum alloy plate for use as a lithographic printing plateof claim 1, which is surface roughened by electrolytic treatment in anelectrolytic solution for electrolytic etching treatment which issupplied by a roll and an AC current is applied to the roll.
 5. Thealuminum alloy plate for use as a lithographic printing plate of claim4, additionally comprising a photosensitive layer on the surfaceroughened by electrolytic treatment.
 6. The aluminum alloy plate for useas a lithographic printing plate of claim 1, in which the value of C/Bis less than 0.8.
 7. The aluminum alloy plate for use as a lithographicprinting plate of claim 1, wherein the AlFe intermetallic compoundparticles have the formula Al_(m)Fe, where 4<m<6.
 8. The aluminum alloyplate for use as a lithographic printing plate of any one of claims 1,2, 3, 6, and 5, and 7, the aluminum alloy plate comprising a metastablephase dispersion layer which is formed from the surface of the aluminumplate to a depth of 2 to 50 μm, wherein the metastable phase dispersionlayer comprises AlFe intermetallic compound particles.
 9. The aluminumalloy plate for use as a lithographic printing plate of any of claims 1,2, 3, 4, 6, 5, and 7 in which the aluminum alloy plate comprises, in wt%, Fe: 0.2 to 0.4%; Si: 0.05 to 0.15%; Cu: 0.001 to 0.003%; Zn: 0.025 to0.08%; Mg: 0.02 to 0.04%; and Ti: 0.005 to 0.02%, and the remainderaluminum and inevitable impurities.